Generally, a process cartridge applying electrophotographic technology comprises at least: a photosensitive drum on which an electrostatic latent image is formed and a developer roller which provides developer on the photosensitive drum to develop the electrostatic latent image. Its image forming mechanism can be roughly described as follows: an electrostatic latent image is formed on a photosensitive drum through an exposure unit such as a laser scan unit corresponding to a digital image signal, the electrostatic latent image is developed through the developer provided from a developer roller, the developed image is transferred onto a recording medium, and the transferred image is fixed on a recording medium through heat and pressure thus to form an image.
A process cartridge is generally divided into a contact process cartridge and a non-contact process cartridge according to whether a photosensitive drum and a developer roller are separated with each other for a predetermined gap. In a contact process cartridge, a photosensitive drum and a developer roller are contacted with each other. A printer exerts a direct current bias voltage on the developer roller. A developer is moved from the developer roller to the photosensitive drum through voltage difference between the photosensitive drum and the developer roller. This type of the development is called a contact development method.
In a non-contact process cartridge, a photosensitive drum and a developer roller are separated with each other for a predetermined gap. A printer exerts a direct current bias voltage and an alternating current bias voltage in an overlapping mode. A developer jumps onto the photosensitive drum from the developer roller. This type of the development is called a jumping development method.
Since bias voltages exerted to developer rollers are different in a contact development method and a jumping development method, the process cartridges of these two development methods can only be used with correspondent printers and cannot universally be used. That is, a contact process cartridge cannot be used in a jumping development printer while a jumping development cartridge can also not be used in a contact development printer.
Currently, there is a process cartridge applying a jumping development method. Its structure is shown in FIG. 1. The process cartridge comprises a toner chamber component 20′ and a waste toner chamber component 30′ that are connected into an integral one through a connection shaft. The toner chamber component 20′ comprises a toner chamber 1′, a magnetic toner 2′, an agitator 3′, a magnetic roller component 4′ and a toner deposit blade 5′. The waste toner chamber component 30′ comprises a waste toner chamber 7′, a photosensitive drum 6′, a cleaning blade 8′ and a charge roller 9′. Compression springs 10′ are provided at the two ends of the toner chamber 1′, respectively. The waste toner chamber component 30′ is stuck together with the toner chamber component 20′ through spring action of the compression springs 10′. The gap between the magnetic roller component 4′ and the photosensitive drum 6′ can be ensured through the interval sets at the two ends of the magnetic roller component 4′. The development mechanism is described as follows: after the magnetic toner 2′ is mixed evenly through the agitator 3′ in the toner chamber 1′, it is carried by a doping vehicle and absorbed on the outer surface of the magnetic roller component 4′ by the permanent core of the magnetic roller component 4′, at this moment, the magnetic toner 2′ does not show any polarity. That the magnetic roller component 4′ carrying the magnetic toner 2′ rotates and is tangent and makes friction to the toner deposit blade 5′ causes the magnetic toner 2′ to take charge. The magnetic toner 2′ forms a very thin and evenly distributed layer of the magnetic toner on the surface of the magnetic roller component 4′ under the action of the toner deposit blade 5′ and the magnetic field. When the photosensitive drum 6′ having formed an electrostatic latent image closes to a certain distance from the carried magnetic toner 2′ through the magnetic roller component 4′, the magnetic toner 2′ jumps to the surface of the photosensitive drum 6′ to form a toner image under the action of developing bias formed by overlapping an alternating current bias voltage and a direct current bias voltage. The photosensitive drum 6′ carrying the toner image acts together with a printer's transfer roller causing the toner image to be printed on a printing paper and then to enter into a fixing system, so does the cycle.
The printing quality of this development method is to control the distance between the photosensitive drum 6′ and the magnetic roller component 4′ mainly through the thickness of the interval sets at the end of the magnetic toner 2′. Especially under the working condition, the photosensitive drum 6′ and the magnetic roller component 4′ are all exited in rotating states. The jump of the photosensitive drum 6′ and the magnetic roller component 4′ can easily change the distance between the photosensitive drum 6′ and the magnetic roller component 4′. So, in order to ensure good printing quality, little change of the distance between the photosensitive drum 6′ and the magnetic roller component 4′ is required. The precise accuracy is required to be 0.01. The accuracy of the cartridge parts is so high that it causes the manufacturing cost to be very high.